This invention pertains to the general art of hermetic refrigerant compressors and particularly to multi-cylinder compressors of this type which have the cylinders arranged radially about a vertical crankshaft.
In compressors of this type a condition occasionally arises in which oil and/or liquid refrigerant collect in the lowermost cylinder heads during extended shutdowns. The accumulation of the liquid can be the result of any of several different conditions such as excessive oil in the refrigerant system or excessive liquid refrigerant in the oil, for example. A small quantity of liquid in the cylinder head space of the type of compressor with which this invention deals is not particularly detrimental, since it will be blown out through the discharge pipe at the top of the cylinder head. However, if there is a significant quantity of liquid in the cylinder head space it is unable to get out through the discharge pipe quickly enough upon start-up and may cause damage to the cylinder head or gasket or valves or connecting rods or piston rings. The possibility of damage with a liquid accumulation is more likely with larger compressors which use large three-phase motors with significant starting torque. With smaller compressors of the type such as typically use permanent slit capacitor motors, the likelihood of such damage is not as great since there is relatively less starting torque. However the application of the invention to such smaller compressors can also function to promote more rapid equalization of pressures between the high side and the low side so that easier starting is promoted.
It is an aim of this invention to provide a hermetic refrigerant compressor with an arrangement which avoids the problems which arise if liquid collects in any of the cylinder heads.